db: Made overlap String() prettier and more readable.
db: Made overlap String() prettier and more readable.

Signed-off-by: Bartek Plotka <40733124e8bedaac646d3fd1c538b5cb2b6856fe@gmail.com>

prometheus/prometheus,keegancsmith/prometheus,prometheus/tsdb,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,Gouthamve/tsdb,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,alileza/prometheus,Gouthamve/prometheus,alileza/prometheus,prometheus/prometheus,kangwoo/prometheus,kangwoo/prometheus,prometheus/prometheus,Gouthamve/prometheus,alileza/prometheus,kangwoo/prometheus,alileza/prometheus,kangwoo/prometheus,alileza/prometheus